Department of Advanced Science and Technology, Toyota Technological Institute, Nagoya, 468-8511, Japan.
Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka, 819-0395, Japan.
Chem Asian J. 2022 Apr 1;17(7):e202101243. doi: 10.1002/asia.202101243. Epub 2022 Mar 9.
Carbon-nitrogen bond formation is an important method on both laboratory and industrial scales because it realizes the production of valuable pharmaceuticals, agrochemicals, and fine chemicals. Direct reductive N-alkylation of amines with carbonyl compounds via intermediary imine compounds, especially under catalytic hydrogenation conditions, is one of the most convenient, economical, and environmentally friendly methods for this process. Here we report a novel palladium species on zirconia having specific activity towards hydrogenation of imines but other carbonyl groups remaining intact. The present catalytic property offers a practical synthetic method of functionalized secondary amines by reductive N-alkylation under mild conditions with high atom-efficiency. Mechanistic studies revealed that the catalytically active species is the palladium cluster, which is generated in situ from molecular palladium complexes on the support by exposure to atmospheric hydrogen. These fundamental findings are expected to progress in developing novel cluster catalysts for chemical processes directed towards a sustainable society.
碳氮键的形成是实验室和工业规模上的重要方法，因为它实现了有价值的药物、农用化学品和精细化学品的生产。通过中间亚胺化合物，特别是在催化氢化条件下，将羰基化合物与胺直接还原 N-烷基化是该过程最方便、经济和环保的方法之一。在这里，我们报道了一种新型的氧化锆负载钯物种，它对亚胺的氢化具有特定的活性，但其他羰基基团保持完整。目前的催化性能提供了一种实用的合成方法，可在温和条件下通过还原 N-烷基化以高原子效率得到功能化仲胺。机理研究表明，催化活性物种是钯簇，它是通过载体上的分子钯配合物暴露于大气氢原位生成的。这些基本发现有望促进开发用于可持续社会导向的化学过程的新型簇催化剂。
